222Rn gas diffusion and determination of its adsorption coefficient on activated charcoal

The adsorption coefficient is the fundamental parameter characterizing activated charcoal's ability to adsorb 222Rn. The adsorption coefficient is determined for 222Rn activated charcoal detectors. In addition, a diffusion and adsorption model is developed for the transport of 222Rn in a porous bed of activated charcoal. These processes can be described by parabolic second order differential equation. The equation is numerically solved using the finite differences method. With this model, the 222Rn activity adsorbed in the detector is calculated for diverse situations. (author)